Summer Takumi's IV choice

So, I've got 2 Summer Takumi's with both + Attack but one is -Def, the other is -Res, and I struggle to know which one would be overall best. The -Res one would be able to sustain ''easier'' against DC units to get into Fishie Bow range, but the - Def one would be good for taking out a mage who would most likely put him in Fishie Bow range as well. Would love to get some inputs from people!